Swift

Call a JavaScript Function Returning an Integer

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Demonstrates how to call a JavaScript function that returns an integer. Swift

func chilkatTest() {
    var success: Bool = false

    // ----------------------------------------------------------------------------------
    // The Javascript function called in this example is shown at the bottom of this page.
    // -----------------------------------------------------------------------------------

    // In this example, we'll load the Javascript function definition from a file.
    // It doesn't need to come from a file.  It could just as easily be loaded from a string.
    let sbScript = CkoStringBuilder()!
    success = sbScript.loadFile(path: "js_call_function.js", charset: "utf-8")
    if success == false {
        print("\(sbScript.lastErrorText!)")
        return
    }

    // Note: Each instance of a Chilkat Js object automatically establishes
    // its own internal runtime and context.  Applications do not need to explicitly create
    // the JavaScript runtime or context.
    let js = CkoJs()!

    let result = CkoJsonObject()!
    result.emitCompact = false

    // Call Eval to add the function (shown at the bottom of this page) to the context's global object
    success = js.eval(jscript: sbScript, result: result)
    if success == false {
        // Examine the result for an exception.
        print("\(result.emit()!)")

        // Also examine the LastErrorText.
        print("\(js.lastErrorText!)")
        return
    }

    print("\(result.emit()!)")

    // The expected output is "undefined":

    // {
    //   "type": "undefined",
    //   "value": "undefined"
    // }

    //    When Eval processes a script containing only a function declaration,
    //    it successfully performs the action (the function becomes defined).
    //    However, since the script consists of a statement that produces no value,
    //    the script's overall completion value is empty. In JavaScript, the
    //    absence of a value is represented by `undefined`.
    // 
    //    Therefore, the Eval call returns `undefined`.

    // ------------------------------------------------------------------------------
    // Call the function calculateScore("Player1", 10, 20)

    let funcCall = CkoJsonObject()!

    // Create JSON defining the function call:

    // {
    //   "name": "calculateScore",
    //   "args": [ "Player1", 10, 20 ]
    // }

    funcCall.updateString(jsonPath: "name", value: "calculateScore")
    funcCall.updateString(jsonPath: "args[0]", value: "Player1")
    funcCall.updateInt(jsonPath: "args[1]", value: 10)
    funcCall.updateInt(jsonPath: "args[2]", value: 20)

    funcCall.emitCompact = false
    print("\(funcCall.emit()!)")

    success = js.callFunction(func: funcCall, result: result)
    if success == false {
        // Examine the result for an exception.
        print("\(result.emit()!)")

        // Also examine the LastErrorText.
        print("\(js.lastErrorText!)")
        return
    }

    print("\(result.emit()!)")

    // Output:

    // {
    //   "type": "int",
    //   "value": 37
    // }

    var retval: Int = result.int(of: "value").intValue
    print("retval = \(retval)")

}